1. Field of the Invention
This invention relates to an automatic control device for electronic flash apparatus, and more particularly to a switching circuit of the control device.
2. Description of the Prior Art
In general, flash tubes have to flow large current when flash light is produced. To terminate the duration of energization of the flash tube instantaneously has, therefore, been a very difficult problem. A satisfactory solution for this problem is disclosed in U.S. Pat. No. 3,591,829, in which a flash tube is provided with a silicon controlled rectifier connected in series therewith in combination with a commutation capacitor arranged so that when the flash tube is deenergized, an amount of electrical energy previously shared on the commutation capacitor is applied across the main electrodes of the silicon controlled rectifier to open it. A drawback of this arrangement is to require that the commutation capacitor be of large capacity, which in turn calls for an increase in the dimensions of the electronic flash.